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Highly three–dimensional and complex flow structures are closely related to the aerodynamic losses occurring in the transonic axial–flow compressor. The large eddy simulation (LES) approach was adopted to study the aerodynamic performance of the NASA rotor 37 for the cases at the design, the near stall (NS), and the near choke (NC) flow rate. The internal flow vortex topology was analyzed by the Q–criterion method, the omega (Ω) vortex identification method, and the Liutex identification method. It was observed that the Q–criterion method was vulnerable to being influenced by the flow with high–shear deformation rate, especially near the end–wall regions. The Ω method was adopted to recognize the three–dimensional vortex structure with a higher precision than that of the Q–criterion method. Meanwhile, the Liutex vortex identification method showed a good performance in vortex identification, and the corresponding contribution of Liutex components in the vortex topology was analyzed. The results show that the high–vortex fields around the separation line and reattachment line had high vortex components in the x–axis, the tip clearance vortices presented a high–vortex component in the y–axis, and the suction side corner vortex possessed high–vortex components in the y– and z–axes.

Based on the theory of a low-recoil rarefaction wave(RAVEN)gun firing cased telescoped ammunition(CTA), the equation system of interior ballistics and kinematics also dynamics were established. The dynamic characteristic curves were obtained by numerical simulation analysis, and the results were verified by firing tests. Compared with traditional closed-breech guns, the low recoil force swing chamber gun keeps the projectile’s muzzle velocity basically unchanged, while the maximum recoil is reduced by up to 74%. Based on these results, the parameters of the inertial breech buffer spring were optimized by numerical simulation optimization algorithms which efficiency is faster than using virtual prototyping technology, while the maximum recoil force of the breech reduced by 14.2% without affecting system performance and structural installation size, which effectively improved the overall performance of the weapon system.

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The phenomenon that droplets impacting on the solid surface is ubiquitous in industrial applications such as spray cooling, spray painting, ink-jet printing, and fuel-air mixing internal combustion engines. The dynamic of droplet impacting on solid surface has been a hot topic in the area of fluid mechanics. Most of the existing experimental studies focused on the droplet impacting on flat or cylinder surface whereas the droplet impacting on a dry sphere surface, especially its effect from the sphere curvature, has been less investigated. Therefore, the dynamic behavior of a droplet impacting normally on a dry sphere is experimentally investigated at the relatively high Reynolds and Weber number in the present work. The impacting velocity of the droplet on the sphere is discussed with consideration of air resistance effect. The influences of spherical curvature and Weber number on the dynamic behavior and spreading factor are analyzed. The experimental results are compared with those of previous impacting flat researches. The results show that the drop velocity fluctuates significantly near the impacting sphere. The influence of the spherical curvature on the dynamic behavior of the droplet impact is obvious. The maximum spreading diameter of the liquid film will exceed that of the sphere with a curvature greater than 0.2 mm^–1, and some segments of the liquid film rim even slide down directly. When the spherical curvature is less than 0.167 mm^–1, the dynamic behaviors of the impacting droplet will undergo the spread, retraction, oscillation, and stable attachment after impacting. Then the maximum spreading factor of the droplet impacting sphere is little influenced by the curvature, and gradually tends to that of the droplet impacting plane with curvature decreasing. The Weber number has little influence on the spreading velocity of the liquid film, but obvious on the retraction. The maximum spreading factor gradually increases with Weber number increasing. A simple empirical correlation for the maximum spreading factor is obtained. This study conduces significantly to further investigating the dynamic characteristics of droplets impacting on the sphere.